1. Field of the Invention
This invention relates to multimedia multiparty communications systems and, more particularly, to methods for interfacing with application programs and for managing resources used for multimedia, multiparty communications. The invention facilitates the management of resources for multimedia, multiparty communications by providing a common framework for application developers to use to indicate when resources are required for multimedia multiparty communications and when resources are no longer required for multimedia multiparty communications. The invention further facilitates the management of other aspects of communications such as negotiation.
2. Description of the Related Art
The Windows Telephony Application Programming Interface (WTAPI) provided a framework for programmers to develop user applications that use the telephone. WTAPI permitted programmers to combine the graphical user interface (GUI) capabilities of Microsoft Windows with telephony applications. WTAPI also permitted integrated messaging for user applications, which permits users to use their computers for electronic mail, voice mail, and to receive incoming facsimiles.
Although WTAPI allowed programmers to produce certain types of telephony applications, these applications could not take advantage of the many other developments in the telecommunications industry.
For example, the telecommunications industry has been developing new telecommunications networks called broadband networks, such as B-ISDN, which can simultaneously transmit sound, video, and data. Broadband networks may include new protocols for multimedia communications and additional functions based on new network resources such as multimedia hardware for mixing, combining, and transcoding sound, video, and data from different sources.
Broadband networks will permit multimedia, multiparty calls between users with heterogeneous desktop computers or other terminal equipment. User applications cannot handle multimedia, multiparty calls using WTAPI. To do so requires a framework, including sophisticated methods for managing multimedia multiparty calls. Such a framework must permit several user applications to combine many calls using multimedia hardware, regardless of whether the hardware is in the broadband network or in the terminal equipment (e.g. desktop computer). The framework must also permit several independently-developed applications to share control of different aspects of the same multimedia multiparty call.
WTAPI cannot support this framework because WTAPI does not logically distinguish between different objects, such as multiple parties, communications services, or communications links, that make up multimedia multiparty calls. WTAPI users can only manage a call as a monolithic object.
In addition, WTAPI requires application developers to write separate program code to handle multiparty hardware which mixes, combines, and transcodes sound, video, and data located in the broadband network and locally at a desktop computer or local area network.